The present invention relates to predicting subterranean formation damage caused by deformable additives present in treatment fluids and related compositions and methods.
Exploration and production of subterranean fluids often involves placing treatment fluids into the subterranean formation for various purposes. The treatment fluids in subterranean formations may include deformable additives, i.e., having a morphology that deforms. As used herein, the term “treatment,” or “treating,” refers to any subterranean operation that uses a fluid in conjunction with a desired function and/or for a desired purpose, e.g., drilling, stimulation, sand control, fracturing, wellbore strengthening, fluid loss control, and completion operations. The term “treatment,” or “treating,” does not imply any particular action by the fluid.
Depending on the nature of the subterranean formation, deformable additives may lead to formation damage that can be costly and time consuming to repair. For example, subterranean formations with low porosity may be susceptible to pore plugging when deformable additives are employed. As a deformable additive passes through a pore, the additive and fluid will experience extensional flows through the pore. During extrusion the deformable additive may deform into an elongated morphology, which can be a highly strained conformation that becomes substantially immobile, and therefore plugs the pore.
Three primary avenues to removing the additive now having an elongated morphology from a pore may include allowing the structure to relax into a less strained conformation, applying a high back-pressure to push the additive out, and degrading the additive into smaller components that are more easily removed from the pore. Each of these methods are time-consuming, however, and potentially costly, and bring with them the potential for further damage, e.g., acidizing to degrade a gelling agent may remove the gelling agent but can also cause undesirable damage to the faces of the formation.
Alternatively, the subterranean formation may be fractured to return at least some of the permeability. This avenue may not address the underlying problem of pore plugging, however, because it creates new fractures and pores for formation fluids to flow rather than ameliorating the plugging.
To mitigate the potential of formation damage from deformable additives, return permeability tests can be performed. Return permeability tests often involve a multistage process that can take up to two-days and cost tens of thousands of dollars to test a single treatment fluid having a deformable additive, in addition to the rig down-time. Further, return permeability tests typically involve core samples, which can be inconsistent and introduce a high degree of uncertainty into the testing.
Methods that are faster and less costly for the prediction of formation damage from treatment fluids having a deformable additive may be of value to one skilled in the art.